The clinical signs that can occur in an infected goat are mainly due to the body’s reaction against the virus-infected cells.

Clinical signs include:

*            viral mastitis (increased white blood cells in the milk). May progress to ‘hard udder’ (indurative mastitis)

*            arthritis in any joints, due to inflamed tendon sheaths and joint linings (‘big knee’),

*            pneumonia

*            progressive paralysis.

Kids less than 6 months of age are more likely to show disease of the nervous system.

Most CAE infected goats show no clinical signs, especially when well-managed, but does may develop viral mastitis. Clinical signs can begin if an infected goat is stressed e.g. poor nutrition and overcrowding.

There are two pathways which can be followed for the eradication of CAE. The first is a test and cull, based on three monthly testing and segregating the test negative animals. The second pathway is a snatch-rear and segregation of the newborn animals as a separate herd thereby establishing two herds. For the latter approach to succeed, a robust biosecurity plan must be in place and a closed herd maintained. Both methods have been used successfully in Australia and overseas.

Infected goats are detected by serological testing. The most accurate test is the ELISA test although some countries still use the less specific AGID test.  There can be significant delays between infection and development of antibodies.

Repeated blood testing over 12 months will detect most infected goats (a very small number may take longer to seroconvert).

All goats 6 months and older should be tested. Do not test adult does in the month either side of kidding as inconsistent results could occur.  Do not test goats within a month after any vaccination.

CAE spreads mainly by kid goats drinking milk from infected does. Adult goats can also be infected by exposure to infected milk droplets during milking.

CAE can also be spread by respiratory secretions, saliva and tears when goats are kept in close quarters.

Infection may be spread by blood on equipment such as vaccination needles, tattooing equipment, dehorners and foot/hair shears, or through exposure to open wounds.

Venereal spread in semen and in-utero spread to kids, are less likely but can occur.

The virus usually enters a clean property in an infected goat.  The key to preventing CAE spread is to detect infected goats that have no signs of disease.

People drinking milk from infected does can develop antibodies to the CAE virus. There is no evidence that this contact has resulted in persistent viral infection.

The surface glycoproteins on the CAE virus and the HIV virus cross react. It has been suggested that exposure to the CAE virus in goat milk may lead to false positive reactions to HIV in some people.

The virus

The CAE virus belongs to a family of viruses (lentivirus) that can integrate into the DNA of a host cell and then use the host’s own cell to reproduce itself (retrovirus). Once a host cell is infected, it remains infected for life. The only way to remove infection is to destroy the infected cell.

The CAE virus infects mainly white blood cells and travels through the body inside these cells. Any secretion that contains white blood cells (milk, blood, saliva, tears, respiratory secretions) will contain the virus. It can also be found in the cells surrounding ova (egg cells) and in semen.

Antibodies to the virus don’t provide protection but are good indicators of exposure and infection. It can take two months, and rarely up to two years, for antibodies to develop after exposure to the virus.

The virus is very susceptible to inactivation by heat (56 degree C for 10 minutes) and by chemical disinfection but is resistant to ultraviolet radiation. It does not survive well outside the host as it is cell-associated.

The disease

The disease occurs when the cells carrying the latent virus mature and multiply in different body ‘target’ organs – mammary gland, lungs, tendons sheaths, joints and nervous tissue.

The clinical signs that can occur in an infected goat are mainly due to the body’s reaction against the virus infected cells.

CAE risk factors

The lowest-risk herd is a CAE-accredited herd or a herd that has no introductions (closed herd) and annual negative whole-herd blood tests.

Low risk factors include:

*            extensive management where single doe/kid(s) units predominate and where goat to goat contact is minimal (commercial fibre and meat goats)

*            kids fed pasteurised milk (heated to greater than 56 degrees C for a minimum of 10 minutes)

*            strict hygiene in the use of common equipment or when handling goats.

A low to moderate risk herd is a herd with a history of negative testing that buys in goats (open herd).  Goats bought from CAE accredited herds or from closed herds with a good testing history would pose a low risk.  Goats bought from herds with no testing history present a moderate to high risk (even if the purchased goat is tested).

A high-risk herd is a herd that has not tested all goats over 12 months of age in the last 12 months (including goats that had previously been tested negative or were sourced from tested herds), regardless of introduction policy.

High risk factors include:

*            feeding pooled milk to kids and/or adult goats,

*            exposure to feed or water contaminated with body fluids

*            keeping goats in close confinement

*            sharing unsterilized equipment between goats

*            persons handling a number of goats (especially udder or mouth) from different sources

*            untested goats being milked as a common group

*            mixing of goats from different farms at one site, e.g. at shows and sales.

Shows, sales and any other venues where goats are kept from multiple sources are a significant transmission risk. The risk increases the longer the goats are kept together.

CAE Accreditation

Market Assurance Programs (MAP’s) are voluntary programs for producers to identify and promote their high assurance (low risk) disease status to clients.  Animal Health Australia (AHA) manages the Australian Market Assurance Program for Goats (GoatMAP).

Further information on the GoatMAP program can be obtained from Animal Health Australia’s website

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